Class IEC 2 surge arrester 3EQ series

for substationsarc protectionfor transient current protection

Product overview
High-voltage surge arresters protect electrical infrastructure from transient overvoltages caused by lightning, switching operations and other disturbances. Siemens Energy offers a portfolio of arresters for medium to ultra-high voltage applications, with product families designed for demanding environmental and mechanical conditions.

Key functions and features

• Overvoltage protection: Rapid diversion of transient voltage peaks to protect equipment.
• Equipment safety: Prevents insulation breakdown to extend asset life.
• System reliability: Reduces downtime and maintenance needs for continuous power delivery.
• High mechanical stability: Designs for seismic zones and high-wind regions, suitable for support applications.

Product families and designs

• 3EL silicone Cage Design™: Directly molded silicone rubber housing with an FRP rod cage. Suitable for station and line arresters up to 800 kV. Moisture-tight molding onto MOVs and cage; soft silicone housing enables arc discharge without structural damage or ejection of internal parts. Hydrophobic, UV-resistant, fire-retardant silicone supports low-maintenance operation.
• 3EQ silicone composite hollow core: Silicone housing molded onto a fiberglass-reinforced hollow core for exceptional mechanical strength. Special flange seals prevent moisture ingress and partial discharges. Directional pressure relief devices provide safe arc escape in overload or short-circuit events. Can serve as station arresters or support insulators in seismic and high-wind areas.
• 3EP porcelain design: High-quality porcelain housing with advanced sealing and directional pressure relief. Designed to avoid ejection of internal parts during faults and to withstand severe mechanical loads, making it suitable for harsh environments and support functions.

Technical highlights and benefits
Siemens Energy solutions address high-voltage project requirements with variants optimized for voltage class, mechanical strength and environmental performance. Choose between silicone-molded, composite hollow core and porcelain housings according to site conditions and installation constraints.

Comparison (feature table)
Feature | 3EL silicone Cage Design™ | 3EQ composite hollow core | 3EP porcelain design
Maximum voltage | Up to 800 kV | Up to 800 kV | Up to 800 kV
Mechanical strength | High (FRP rod cage) | Very high (FRP hollow core) | High (porcelain housing)
Housing material | Silicone rubber (hydrophobic, UV-resistant) | Silicone rubber + FRP hollow core | Porcelain
Overload safety | Soft silicone allows safe arc escape | Directional pressure relief devices | Directional pressure relief devices
Maintenance | Maintenance-free for silicone designs | Long-term reliable operation | Robust in harsh environments
Application flexibility | Station or line arresters | Station arresters in seismic/high-wind zones | Station arresters in seismic/high-wind zones
Weight | Lightweight | Moderate | Heavier but durable

Applications

• Transmission and distribution substations: Protection of substation equipment against transient overvoltages.
• Power transformers and reactors: Protection to ensure reliable operation and asset longevity.
• Switchgear and control equipment: Safeguarding control systems and switchgear.
• Overhead and underground lines: Protection for transmission corridors and cables.
• Challenging environments: Coastal, desert, polluted-air regions, seismic and high-wind zones.

Design & environmental features

• Reliable pressure relief systems for safe operation under overload.
• Pollution-resistant profiles delivering stable performance in coastal and polluted environments.
• Advanced sealing and flange seals to prevent moisture ingress and partial discharges.
• Materials selected for environmental compatibility and long service life.

Downloads
High-voltage surge arresters brochure (PDF, 3 MB).

Technical specifications

• Voltage range (product family): solutions available up to 1,200 kV; typical models specified up to 800 kV.
• Housing materials: silicone rubber (hydrophobic, UV-resistant, fire-retardant) and high-quality porcelain.
• Mechanical structure: FRP rod cage (3EL), FRP hollow core (3EQ), porcelain housing (3EP).
• Sealing: advanced flange seals to prevent moisture ingress and partial discharges.
• Overload safety: soft-silicone arc escape (3EL) or directional pressure relief (3EQ, 3EP).
• Application types: station arresters, line arresters, support insulators; suitable for seismic and high-wind zones.
• Maintenance: maintenance-free for silicone-housed arresters; designs optimized for long-term reliable operation.
• Environmental suitability: designed for coastal, desert and high-pollution areas.